Engine combustion regulating device



Jan. 4, 1949. c. w. M MILLAN ENGINE COMBUSTIdN REGULATING DEVICE Filed May 9, 1946 VII/1 5 'xx ximxxxx \\X $0 l 2, SheetsF-Shut 1 INVENTOR Jan. 4, 1949. c. w. M MILLAN 2,453,036

ENGINE COMBUSTION REGULATING DEVICE Filed ma 9, 1946 I ZSheets-Sheet 2 .mIH

INVENTOR Pmatea na 4, 1949 umrno STATES PArnNr OFFICE ENGINE cormus'rron nncnna'rmo nvrca Charles w. MaoMillan, Alexandria, vs. Application May a, 1940, Serial No. 688,615

This invention relates to engine ignition controlling systems and particularly to engine indicator devices as applied. to automatic adjustment of ignition, air-fuel ratio, and fuel injection timing. The use of engine indicators in engineering laboratory work for exploring phenomena occurring in the combustion chambers of engines is Claims. (01,122,411).

well known, and many different types orapparatus have been devised for this purpose. One of the principal difficulties encountered. with apparatus of this type has been in the provision of a satisfactory pressure-responsive unit to be inserted in the engine cylinder head and in con tact with combustion chamber gases. Many designs of such units have been made to operate satisfactorily for engineering purposes, but under continued operation frequentreadjustment, recalibration, or general servicing is required. Furthermore, engine indicators have in general been too expensive and complicated for other than laboratory use.

A primary purpose of this invention is to provide a pressure-responsive unit which may be inserted in an engine cylinder head in contact with combustion gases and which will respond to any predetermined pressure to which the device may be adjusted, the response of the device consisting of closing an electric circuit for operation of engine regulating apparatus.

For descriptions of various associated apparatus reference is made to my Patent No. 2,394,792, dated February 12, 1946, setting forth description of an Engine ignition controlling device." Reference is also made to my co-pending application, Serial No. 621,309, filed October 9, 1945, for an Engine fuel controlling device.

Another object is to provide an engine indicator, responsive to combustion chamber gas pressure, the design of which precludes the necessity for frequent readjustment.

Another object is to provide a device for indicating maximum combustion chamber pressure and associated apparatus for automatically producing engine operating adjustment.

Still another object is'to provide a device which is responsive to engine combustion chamber gas pressure for the purpose of controlling detonation.

Other objects and singular features will become apparent from the following description.

In the drawings Figure 1 is a sectional view of the pressure responsive unit to be inserted in an engine cylinder head;

Figure 2 is a plan view, and Figure 3's, bottom view of the unit illustrated in Figure 1;

Figure 4 is an enlarged partial view of Figure 1 1 illustrating a central liquid passage with pulsation dampening means;

Figure 5 is a representative diagram illustrating a, combination of parts for a practical application of the device.

A detailed description is as follows: In Figure 1 a housing I having a threaded extremity 2 and hexagonal portion 3 is fitted with a cap 32 having air inlet holes 30. A bushing I having selected thermal properties is inserted in the end of body I and secured therein by means of threads 8. A circular piece 5 with perforations 6 is removably attached to the lower end of bushing I and retains athin diaphragm 4 so as to seal the end of said bushing 1 against leakage. An internal casing 9 contains ceramicor insulated body Ill having a passage I I and a series of cup-like pieces I4, each of the latter embodying a restricted oriflce. The lower end of ceramic body In is retained in casing 9 by open plug I5. A liquid, such as mercury, I6 is contained in the space above .diaphragm 4 and extends upward through passage II to a predetermined position l3. A retaining nut I1 holds the lower end of body 9 in sealed condition within bushing 1. The upper end of casing 9 is fitted with a threaded cap I8 retaining the upper end of ceramic body III in alignment. Flexible bellows 2I encloses the upper extremity of easing 9 and body I0. An electrical contact or electrode I9 extends into passage II to an adjustable position from a supporting piece 23 from which it is insulated by washers 24 and to which it is secured by nut 26. A closing cap 25 provides a mechanical contact for adjusting screw 28; the

latter having knurled head 33 as well as friction spring 29, calibration dial 3| and pointer 34 in its assemblage. An insulated conductor 21 electrically communicates with electrode I9. Spring 22 bears against piece 23 and cap I8 exerting an extending force on bellows 2|, A flexible or elastic nipple 20 encloses the upper opening of passage I I in body I0 while permitting electrode I9 to be slidably adjustable therein. A tube 35 is inserted through housing I and casing 9 for cooling purposes.

A representative application of the device is illustrated in Figure 5 in which 36 represents an engine piston. Cylinder head 31 contains a spark plug 38 and pressure-responsive unit the housing of which is denoted by I. Illustrative of engine regulating sub-devices are carburetor 48 with electromagnetic fuel metering control 41, and

ignition distributor 45 with electromagnetic spark adjusting control 48, shown connected in circuit with current source i and relay I8 by means oi conductors 42, 4!, 44, and 52. Optional switches 49 and it are illustrated as desirable details but may be eliminated without altering the practical operation of the device. Conductor 21 connects the electrode II o! the pressure-responsive device as shown in Figure 1, with relay '9 which is operatively connected to current source Bl through conductor 4| and ground G." A small dampening piston 54 operates in cylinder 56 between compression spring 51 and air trapped by check valve 55. Arm 53 connects piston 54 with moving components of relay I9. Tube 35 is normally connected to a vacuum source such as the intake manifold 02 the engine.

In operation gas pressure resulting Irom cornbustion within the engine combustion chamber exerts pulsating lorces against flexible diaphragm 4 through openings 6. Each principal pulsation of force so exerted acts coincidentally with the combustion portion of the cycle of piston motion. since diaphragm 4 is sufflciently thinto elastically respond by a small amount, a few thousandths oi an inch or less, to the intermittent combustion pressure, the latter is transmitted in reduced magnitude to the mercury or other suitable liquid II; which is as a result forced upward, in opposition to the i'orce of gravity, through passage II to a height proportional to the intensity of the actuating gas pressure. Pulsation dampening is obtained in passage II by means of a series of restricted openings through which the liquid must pass. Thus the transmitted cyclic character of the actuating gas pressure is resisted by fluid friction to the end that an immediate but steady rise or fall of the liquid level I! in passage ll takes place in response to, and in proportion to, the intensity of combustion chamber gas pressure. Although other electrically conducting liquids may be suitable, it is contemplated that mercury is the most desirable for this application since it is relatively stable, readily available commercially and possesses a boiling point above the temperature which will be encountered in this application. Electrical contact with electrode I9 is made at the mercury level I3 when the latter rises to the pre-set position I 2 of the end of said electrode. Since the mercury body I8 is in contact with metal bushing 1, the electrical circuit is continued through the housing I and thence to the engine cylinder head ground.

Compensation for thermal expansion of liquid body It is provided for in the construction of bushing 1 which is preferably made oi a material having a coefficient of expansion closely similar to that of the liquid. For example, lead alloy might be used. The lower end of bushing l is free to expand downwardly away from its supporting threads 8 thus increasing the volume of the space occupied by liquid l6. Compensation for an increase in this liquid volume due to temperature rise is thereby provided.

It is evident that adjustment of screw 28 to a selected position of pointer 34 relative to dial 3! will adjust the position [2 of the end of electrode I! to a desired point relative to liquid level II. Such adjustment would normally be made with the engine operating under a detonating condition so as to produce closing of the electric contact between mercury i6 and electrode 19 as detonation tends to occur. The closing of the mercury-electrode contacts within the p essu eresponsive unit of Figure 1 causes current to flow from battery 5| through conductors 4|, 21, and ground G, thus actuating relay 39 which closes circuit 42 with ground G causing a relatively large current to flow from battery 5i through electromagnetic actuating controls 41 and 48; these controls immediately function to adjust the air-fuel ratio and the ignition timing to preclude detonation within the engine combustion chamber.

, In order to prevent erratic operation, it is advisable to incorporate means for producing a short delay with mechanical dampening oi the circuit breaking action of the relay 39. This schematic representative means is described as follows. When current flows through conductors 21 and 4| actuating relay 39, piston 54 is moved against spring 51 by the pulling action of arm 54. Suction within cylinder 56 caused by movement of piston 54 unseats ball valve 55 and draws air into the cylinder until piston 54 ceases to move whence ball 55 becomes seated trapping the air drawn in. When current ceases to flow in conductors 21 and 41, relay 39 opens the connection between conductor 42 and ground G." However, this opening action is resisted temporarily by the trapped air in cylinder 56 which escapes at a designed rate past piston 54. Rapid reversals of the relay from a closed position to an open position are prevented while no restraint or delay is imposed on the closing action of the relay when it is opened.

Obviously, the pressure-responsive device as described and illustrated in Figure 1, may be used ior regulating the injection timing of compression-ignition or Diesel engines by suitable electrical controls functioning from relay 39. In such applications, which are definitely contemplated and considered reservable hereunder, the details of spark plug 38, carburetor 46, and distributor would be eliminated, other appropriate linkages being substituted for the two latter parts. i

It should also be understood that the device as described and illustrated in Figure 1 may be employed in a variety of ways including laboratory indicating apparatus.

I claim:

1. An electrical contact device comprising a diaphragm and an electrical conducting liquid, means for supporting said diaphragm for ex posure of one side to combustion chamber gas pressure of an internal combustion engine, the other side of said diaphragm being in contact with said liquid, said diaphragm being supported to permit flexure under combustion gas pressure, said electrical conducting liquid being disposed to rise thru a plurality of orifices as a result of said flexure of said diaphragm, and an adjustable electrode disposed for contact with said liquid rise, connecting circuits and a battery current source for electromechanical control of selected engine regulating accessories and devices.

2. A pressure responsive electrical contact unit comprising a housing and an internal compartment containing a quantity of mercury, said compartment comprising a flexible diaphragm and thermal volume compensating means, an electrically insulated tube extending vertically from said internal compartment and containing an adjustable electrode, said tube containing a series of restricted orifices disposed for admittance of said mercury, an electric circuit in which said mercury and said electrode form the contacts for closing same with a current source and a relay,

said relay being connected in circuit for operating electromagnetic engine regulating devices; said ranged for flexure as a result or-pressure of said combustion chamber gases, and said fluid being disposed to rise as'a result of said flexure, an insulated tube extending upwardly from said diaphragm and containing damping means and passage for said fluid rise, a flexible bellows inclosure housing said adj stable contacting'electrode, and an electric circuit in which said electrode and said fluid comprise the circuit closing and opening contacts, a relay, and associated circuits for operation of selected engine regulating devices in response to operation of said contacts.

4. An electrical pressure-responsive device adapted for operation with an internal combustion engine and comprising a housing fltted to an engine so as to admit the combustion pressure therein, a flexible diaphragm supported in said housing and exposed to said pressure on one side, a compartment within said housing containing a quantity oi mercury, said mercury being in contact with said flexible diaphragm and disposed to rise in an insulated tube, an electrical conductor entering said housing, an adjustable electrode extending downwardly into said tube and connected to said conductor, a series of restricted openings within said tube. and calibrating means to position said electrode in any predetermined position with respect to'the level of said mercury. and an electric circuit containing a current source, a relay and' conductors communicating with said housing and said electrode conductor, the electrode and mercury forming the operating contacts of said circuit for ultimate operation of engine regulating devices connected in circuit with said relay.

5. An electrical pressure responsive device adapted to an internal combustion engine and comprising a flexible diaphragm in contact on one side with combustion chamber gas pressure. a compartment containing mercury and in contact with the opposite side 01' said diaphragm, an insulated tube extending upwardly from said compartment and containing pulsation dampening means together with openings for the passage of said mercury as same tends to rise, and adjustable electrode insulated trom said diaphragm and extending downwardly into said tube, and conductors connecting said electrode and said mercury in circuit with a current source and a relay, said relay being in turn connected in circuit with electromagnetic engine regulating devices.

CHARLES W. MACMIILAN.

REFERENCES CITED The following references are of record'in the flle of this patent:

UNITED STATES PATENTS Number 

